Page 39 - My FlipBook

should not interfere with the withdrawal of the matrix (Fig. i6A). A
triangular cavity should then be cut between the labial and lingual walls,
extending from the gingival to the incisal wall (Fig. 20 B). The labial
and lingual walls should slightly diverge toward the margins, and the
incisal wall should form a slightly obtuse angle with the pulpal wall,
which should be convex so that the pulp in deep cavities may be pro-
tected. The cavity should be as deep as the pulp of the tooth will permit.

Fig. 20. Fig. 21.

The enamel should be removed with chisels and
knife-edge stones. After the enamel margins have
technique
of Cavity been properly formed, the triangular cavity should
Tormation. be cut in the dentine between the labial and lingual
walls (Fig. 20 B), with the special hoe excavator
(Fig. 6 B). In order to break the straight line of cement a shallow groove
should be formed, with a fissure bur, extending from the incisal wall of
the cavity to the incisal edge, between the labial and lingual enamel plates
(Fig. 20 C). After the cavity has been prepared the margins of the
cavity should be properly finished with sharp chisels, finishing burs, and
Arkansas stones.
After the inlay has been constructed, a very shallow groove should

35